1. Field of the Invention
The present invention is directed to a blow-molded plastic hinge. More specifically, the present invention is directed to an easily manufactured blow-molded hinge made with a tongue and recessed portion that may be assembled in a first position and that are retained but allowed to pivot when rotated to any other position.
2. Description of the Related Arts
It is useful to produce plastic parts with integral hinges. Various hinge constructions may be formed into the part to provide the rotation between the components. One construction utilizes a "living hinge" which includes a portion of plastic material connecting the various components. Living hinges experience fatigue when used repeatedly or when used over a wide pivot range.
Another hinge construction includes pins and sockets formed directly within the parts to be joined. This construction can be used with both blow-molding and injection molding. U.S. Pat. No. RE 31,086 teaches a method of forming a blow-molded container having an integrally formed pin and socket (journal). The socket is formed from a flexible wall portion that extends beyond the main body of the lid. The socket flexes over the pins when the lid and base are brought together. The sockets are generally centered at the midpoint of the pins.
While this construction enables the fabrication of an assembly having an integrally blow-molded hinge, the assembly has several disadvantages overcome by the present invention. The assembly in the U.S. Pat. No. RE 31,086 patent requires that the flexible extending sockets flex over the pins. This requires that at least a portion of the assembly be made of relatively thin flexible plastic material. The assembly process also includes the difficulty of forcibly assembling the two components by flexing the socket over the pins. Additionally, the hinge is not self-centering. The socket is made to have a spacing that lies at the mid point of the pins when the base and lid are assembled. This allows the lid to slide transversely along the pins. This transverse movement may result in a misalignment that impairs the ability to open or close the members. The movement also presents an unwanted "play" between the members.
Plastic articles having integrally molded hinges are increasingly used in automotive applications. Cargo carriers, glove box doors, console covers, ash trays, cup holders and access panels are examples of parts that may utilize an integrally formed hinge. It is desirable to fabricate the members to having the hinge components integrally formed thereon in the molding operation. This patent is directed to components that have their hinge components integrally formed in the blow-molding operation. The components are made without additional fasteners, pins or sockets. The parts are made from a rigid plastic material that need not flex to be assembled. This enables the repeatability needed for high speed manufacturing operations and also reduces the possibility of inadvertently damaging the hinge by over flexing one of the components.
The present invention also overcomes the unwanted play in the hinge by providing a self centering feature that aligns the components when assembled. These disadvantages of the prior art are overcome by the hinge construction described and claimed herein.